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In this paper, we benchmark the read/write performance and standby power of several static random access memory (SRAM) cell architectures utilizing 45-nm Si CMOS MOSFET and/or tensile-strainedGe/InGaAs tunnel FET (TFET) devices under low-voltage operation ( 0.2~\text V \le \vert V\text {DD}\vert \le 0.6 V). We then introduce a novel tensile-strained Ge/InGaAs TFET-based SRAM circuit using several access schemes and investigate the impact of cell access design on static and dynamic performance. SRAM cells utilizing outwardaccess transistors exhibit wide read andwrite static noise margins, but suffer from increased read delay times. A 7T SRAM cell architecture is proposed in order to resolve the degraded read delay time. Cell standby energy was found to exhibit a strong dependenceon operational voltage andGe strain state. Variation of theGe strain state from 1.5% to 3% resulted in an up to 98% reduction in cell standby energy ( \vert V\text {DD}\vert = 0.6 V) as compared with similar CMOS-based SRAM cells. These results demonstrate the superior performance of the proposed 7T TFET SRAM design for operation in the low- and ultralow-voltage regime. [ABSTRACT FROM PUBLISHER]

The aim of this research is to examine and analyse the thermal characteristics of the façade modular element. The possibility of optimization of the façade coating with vegetation is examined experimentally in this research, with the aim of improving the thermal characteristics of the façade wall. This element is made of perlite concrete in which the greenery is implanted. The scope of the research is experimental and theoretical testing the possibility for optimizing the façade coating with vegetation. The energy specificities of modular vegetation elements and their contribution to the improvement of the thermal properties of the façade wall are analysed in the experimental part of the research, the elements of vegetation are treated as the elements which influence the decrease in surface temperature of the façade coating. The modular elements in this research are placed on a reference wall surface facing the South. The methodology presented in this paper is based on the study of climate characteristics in city of Belgrade, experimental measurements of test models, and comparative analysis with the reference wall. During the experiment, the data on the external climate parameters and the coefficient of heat transfer through the wall were continuously measured. Conducted measurements and analyses show the vegetation influence on the reduction in surface temperature of the outer wall and the heat passage through the façade coating. The experiment used a modular model and several plant species. It is noticeable that vegetative walls with green areas covered by plant shells play an important role in the harmonization of the parameters of the microclimate in relation to the local environment. [ABSTRACT FROM AUTHOR]

Energy efficient models have become the path to reduce energy consumption and Greenhouse gas emissions in the built environment in many developed countries. According to the Energy Performance of Buildings Directive (EPBD), new buildings constructed within the European Union (EU) countries are expected to be nearly zero energy buildings (nZEBs) by 2020, while new public buildings are expected to adhere to this target by 2018. The Passivhaus approach has been identified by several researchers as a possible roadmap to achieve nZEBs. The meticulous engineering and high standards of the Passivhaus building fabric, in addition to the high comfort levels, are the main reasons behind the success and widespread of the standard. Recently, in 2013 the Passivhaus principles have been applied to an experimental residential project in the hot and arid climate of Qatar. The project is composed of two identical buildings, one built according to the Passivhaus standard and the other according to normal practices in the country. The thermal performance and comfort levels of both buildings were assessed through dynamic simulation and on-site measurements. Results indicated that at least 50% reduction in annual operational energy, water consumption, and CO2 emissions were achieved in the Passivhaus model in comparison to the standard model. This paper aims to highlight the lessons learned through the Passivhaus project; first by exhibiting the Passivhaus criteria that have been met, second by showcasing the outcomes of the project, and third by displaying the barriers and difficulties that have been associated with building according to the standard in Qatar. Finally, recommendations and general guidelines are suggested towards a possible adoption of the Passivhaus standard in Qatar and the Gulf Cooperation Council (GCC) countries [ABSTRACT FROM AUTHOR]

Energy Efficient Building (EEB) design, construction, and operations require the development and sharing of building information among different individuals, organizations, and computer applications. The Representational State Transfer (RESTful) Building Information Modeling (BIM) web service is a solution to enable an effective exchange of data. This paper presents an investigation into the core RESTful web service requirements needed to effectively support the EEB project lifecycle. The requirements include information exchange requirements, distributed collaboration requirements, internal data storage requirements, and partial model query requirements. We also propose a RESTful web service design model on different abstraction layers to enhance the BIM lifecycle in energy efficient building design. We have implemented a RESTful Application Program Interface (API) prototype on a mock BIMserver to demonstrate our idea. We evaluate our design by conducting a user study based on the Technology Acceptance Model (TAM). The results show that our design can enhance the efficiency of data exchange in EEB design scenarios. [ABSTRACT FROM AUTHOR]

• Affordable and adaptable VIP based internal and external retrofitting solutions. • Implementation of VIP based integral retrofitting solutions in two tertiary buildings. • Space heating energy saving analysis before and after VIP based retrofit. • Envelope heat loss coefficient reduction analysis before and after retrofitting. Vacuum insulation panels (VIPs) represent a huge opportunity to achieve nearly zero energy buildings, especially in the retrofitting of existing buildings. VIPs can be applied in conjunction with façade cladding elements, considerably reducing the heat losses or gains from the building by means of very slim wall construction systems or retrofit solutions. However, the fact that VIPs cannot be cut on-site, can be easily damaged during their handling, installation and use and have an envelope that can cause thermal bridging in the junction between panels or when combined with other materials, has hindered their penetration in the construction market. This paper presents two innovative façade retrofitting solutions, a rear ventilated façade and a stud mounted internal solution, that have tackled all these issues and provide thermal transmittances of 0.28 and 0.14 W/m2 K in relatively slim insulation systems of 10 cm widths. Solutions have been installed on the entire façade of two existing buildings located in Bilbao (Spain) and Malmö (Sweden) subjected to an integral rehabilitation process, covering 2100 m2. Buildings energy use have been monitored before and after the renovation, showing energy cuts of around 35% from pre-intervention status. This paper presents the lessons learnt during the design and installation process of the vacuum insulation integrating solutions in the façade of two existing buildings and the thermal performance results achieved after their retrofitting. [ABSTRACT FROM AUTHOR]

The development of new building materials is a crucial engine for promoting the development of green energy efficient buildings. In this paper, based on the excellent properties of light guiding of resin materials, a new type of resin translucent mortar-based concrete (RTMC) was researched; meanwhile, transmittance properties, mechanical properties, and thermal performance were studied, respectively. The results showed that the resin material possessed excellent light transmittance within the thickness of 100 mm, which can be as high as 93%. Moreover, when the area ratio was within 5%, the compressive strength of RTMC was close to that of plain concrete. Besides, RTMC had excellent thermal performance that the thermal conductivity of RTCM was 0.3815 w/(m·K), which was 60% lower than 0.89 w/(m·K) of plain concrete. [ABSTRACT FROM AUTHOR]

Highlights • A pre and post renovation energy use analysis of almost 90,000 renovated dwellings. • The (p)rebound effects explain only partly disappointing energy renovation results. • Effectiveness of renovations are dependent on state of building prior to renovation. • Effectiveness of renovations are dependent on type of occupant. • Deep renovations often save less energy than expected but are the most effective. Abstract Energy renovations often result in lower energy savings than expected. Therefore, in this study we investigate nearly 90,000 renovated dwellings in the Netherlands with pre and post renovation data of actual and calculated energy consumption. One of the main additions of this paper, compared to previous studies on thermal renovation, is that it only takes dwellings into account with the same occupants before and after renovation, using a large longitudinal dataset. Overall this paper shows new insights towards the influence of the energy efficiency state of a building prior to energy renovation, the type of building, the number of occupants, the income level of the occupants and the occupancy time on the actual energy savings, the energy saving gap and on the probability of lower energy savings than expected. We also investigate if the influence is different per type of thermal renovation measure. Some of the findings are: it is impossible to conclude which single thermal renovation measure is the most effective because this is dependent on the energy efficiency of the building prior to the energy renovation, type of building, income level and occupancy; occupants with a high income save more energy than occupants with low income; dwellings with employed occupants benefit more from improved building installations than dwellings occupied by unemployed occupants; The prebound and rebound effects are only part of the explanations for lower than expected energy savings; Deep renovations result more often in lower than expected energy savings than single renovation measures but nevertheless they result in the highest average energy saving compared to other thermal renovation measures. The results could be used for more realistic expectations of the energy reduction achieved by thermal renovations, which is important for (amongst others) policy makers, clients and contractors who make use of energy performance contracting, home owners, landlords and (social) housing associations and as a starting point to improve the energy calculation method. [ABSTRACT FROM AUTHOR]

Smart metering and fine-grained energy data are one of the major enablers for future smart grid and improved energy efficiency in smart homes. Using the information provided by smart meter power draw, valuable information can be extracted as disaggregated appliance power draws by non-intrusive load monitoring (NILM). NILM allows to identify appliances according to their power characteristics in the total power consumption of a household, measured by one sensor, the smart meter. In this paper, we present an NILM approach, where the appliance states are estimated by particle filtering (PF). PF is used for nonlinear and non-Gaussian disturbed problems and is suitable to estimate the appliance state. ON/OFF appliances, multistate appliances, or combinations of them are modeled by hidden Markov models, and their combinations result in a factorial hidden Markov model modeling the household power demand. We evaluate the PF-based NILM approach on synthetic and on real data from a well-known dataset to show that our approach achieves an accuracy of 90% on real household power draws. [ABSTRACT FROM PUBLISHER]

The main purpose of this paper is to present an evaluation of the in-use energy performance of the Richard Feilden House student accommodation at Queen Mary University, London, UK. The building was completed and occupied in October 2007 and the study was conducted over a 2-year period (January 2008–December 2009). Analysis of the energy audit carried out as part of the study is presented in this paper. The findings suggest that the energy performance of the Richard Feilden House student accommodation is in accordance with its design intent and better than the Good Practice Benchmarks. High levels of insulation, thermal mass, ventilation heat recovery, decentralised electric heating, a greater reliance on internal heat gains for space heating and a proactive building management approach have contributed to this success. However, strategies similar to those adopted by the Passivhaus Standards will be required if future targets of low-carbon buildings are to be met. Currently, there is limited knowledge on the in-use energy performance of student housing in the UK, and while the findings from this study can be helpful for benchmark comparison, more such studies of this building types in the UK are required. [ABSTRACT FROM PUBLISHER]

The K-coverage configuration that guarantees coverage of each location by at least K sensors is highly popular and is extensively used to monitor diversified applications in wireless sensor networks. Long network lifetime and high detection quality are the essentials of such K-covered sleep-scheduling algorithms. However, the existing sleep-scheduling algorithms either cause high cost or cannot preserve the detection quality effectively. In this paper, the Pre-Scheduling-based K-coverage Group Scheduling (PSKGS) and Self-Organized K-coverage Scheduling (SKS) algorithms are proposed to settle the problems in the existing sleep-scheduling algorithms. Simulation results show that our pre-scheduled-based KGS approach enhances the detection quality and network lifetime, whereas the self-organized-based SKS algorithm minimizes the computation and communication cost of the nodes and thereby is energy efficient. Besides, SKS outperforms PSKGS in terms of network lifetime and detection quality as it is self-organized. [ABSTRACT FROM AUTHOR]

This article explores a number of current issues and challenges in sustainability, both of and in academic libraries of the future, using as a case study the new library opened at Macquarie University, Sydney in 2011. Issues covered include sustainable design and operation of library buildings, sustainability in relation to library collections, and the reframing of library organisational design and service provision for the future. [ABSTRACT FROM AUTHOR]

The reduction of energy consumption is a growing concern at the global level. An important domain where the reduction of energy consumption can be achieved is public lighting. Energy charges for street and pedestrian lighting applications represent the largest part of all expenses for public lighting. This is conditioned by many factors, one of them being the use of energy in-efficient lamps and ballasts. This paper's goal is to present and underline possibilities to reduce energy consumption in public lighting systems by the use of energy efficient lamps and ballasts. Some solutions used nowadays to increase efficiency in public lighting are represented in the paper. The results of a search regarding to existing solutions to fulfill the increase of the public lighting network performances will be presented. These will include energy efficient solutions for every type of lamp and energy efficient solutions for lamp and ballast combination used in street and pedestrian lighting applications. [ABSTRACT FROM AUTHOR]

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Phase change materials (PCMs) are used in novel thermal insulating materials in order to exploit their high apparent thermal capacity, which is particularly interesting for buildings with moderate thermal inertia because PCMs have a high potential for CO 2 reduction in lightweight buildings and their energy consumption as well as for increasing the thermal comfort of the inhabitants. In addition, one of the most promising applications of PCMs is embedding them directly in the insulation layers of a lightweight wall. In fact, due to their apparent thermal capacity, light insulators with embedded PCM particles have good performances in smoothing and shaving of thermal peak loads. Furthermore, in some climatic conditions, they can act as thermal storages by reducing thermal loads in buildings. Many sectors of evidence in the literature indicate that it is necessary to use a hysteresis model with two different curves of specific heat versus melting and solidification to assess the transient thermal performance of PCMs embedded precisely in an insulation layer. The main aim of this research is to develop a detailed dynamic model in order to calculate the effects of PCMs in insulation layers of lightweight walls. In this paper, the results of some actions, used to improve the effectiveness of the models, are investigated. In particular they are the adoption of two distinct c p curves, which improves the accuracy of dynamic simulations and, hence, allows the development of the model using a smaller number of points and a larger time step. Several experimental tests validate the numerical model. Furthermore, this paper presents the way in which the position of the PCM insulation layer, in a typical wallboard, affects the temperature and heat flux, inside each layer, in transient conditions. The results show that, in the case evaluated, the maximum reduction of heat consumption, of about 15%, was obtained when PCMs are located in positions three and four, which are approximately in the middle of the wall. In addition, this specific kind of insulation layer generates a delay of the maximum heat flux that is of about two hours. [ABSTRACT FROM AUTHOR]

Major problems worldwide are environmental concern and energy shortage along with the high consumption of energy in buildings and the lack of sources. Buildings are the most intensive energy consumers, and account for 40% of worldwide energy use, which is much more than transportation. In next 25 years, CO2 emissions from buildings are projected to grow faster than in other sectors. Thus, architects must attempt to find solutions for managing buildings energy consumption. One of new innovative approaches is Biomimicry, which is defined as the applied science that derives inspiration for solutions to human problems through the study of natural designs' principles. Although biomimicry is considered to be a new approach for achieving sustainable architecture, but there is still not enough access for architects to make use of it, especially to implement biomimetic design strategy in architectural project. The main objective of this paper is to raise awareness of architects making use of biomimetic strategies with better accessible facility. We propose to create the tool setting relationship to formalize and bridge between biological and architectural knowledge, along with investigative tools to investigate the ability of reducing energy consumption by applying the biomimetic strategies on efficient-energy building design. This article hypothetically proposes an investigative tool based on Bayesian networks for testing the rapid result of choices from natural devices according to specific multi-criteria requirements in each case study. [ABSTRACT FROM AUTHOR]

The design of a complex power supply infrastructure and the satisfaction of the concentrated high energy demand is a constant challenge for data centre owners. Furthermore, economics of the operation and ideas of sustainability are getting more and more attention lately as well. Green data centres are designed to minimize the effect on the natural environment. One of the primary goals of such units is to decrease the energy needs both for the computing infrastructure and the supporting systems (e.g. thermal management), which can be achieved either by increasing the efficiency of processes or by integrating renewable energy sources. Present paper introduces results of an ongoing research and development cooperation between the Centre for Energy Research of the Hungarian Academy of Sciences and Persecutor Ltd., supported by the Hungarian Government’s “PIAC_13” programme. The project aims to develop a new, highly energy efficient data centre infrastructure, which is able to supply IT needs at a high-level, while minimizing power losses. Present paper focuses on decreasing power losses in the distribution and power conversion infrastructure. A power loss model, capable of supporting the optimal selection of different subsystems of the technological chain, is introduced and two case studies are shown to demonstrate the effect of different loss reduction options. [ABSTRACT FROM AUTHOR]

Purpose: Due to the large quantity of data that are recorded in energy efficient buildings, understanding the behavior of various underlying operations has become a complex and challenging task. This paper proposes a method to support analysis of energy systems and validates it using operational data from a cold water chiller. The method automatically detects various operation patterns in the energy system. Methods: The use of k-means clustering is being proposed to automatically identify the On (operational) cycles of a system operating with a duty cycle. The latter's data is subsequently transformed to symbolic representations by using the symbolic aggregate approximation method. Afterward, the symbols are converted to bag of words representation (BoWR) for hierarchical clustering. A gap statistics method is used to find the best number of clusters in the data. Finally, operation patterns of the energy system are grouped together in each cluster. An adsorption chiller, operating under real life conditions, supplies the reference data for validation. Results: The proposed method has been compared with dynamic time warping (DTW) method using cophenetic coefficients and it has been shown that the BoWR has produced better results as compared to DTW. The results of BoWR are further investigated and for finding the optimal number of clusters, gap statistics have been used. At the end, interesting patterns of each cluster are discussed in detail. Conclusion: The main goal of this research work is to provide analysis algorithms that automatically find the various patterns in the energy system of a building using as little configuration or field knowledge as possible. A bag of word representation method with hierarchical clustering has been proposed to assess the performance of a building energy system. [ABSTRACT FROM AUTHOR]

For gas cogeneration system, there are problems to be solved. There is great heat transfer temperature difference in the heat-exchange progress. It can cause huge irreversible loss of heat transfer. More seriously, exhaust temperature of flue gas is generally more than 90°C. The part of the heat is equal to the 40 percent of heating load. The return water conventionally has a high temperature, so the flue gas waste heat is difficult to recover. Based on the situation, this paper introduced the technique of flue gas waste heat recovery in gas cogeneration based on absorption heat-exchange. Absorption heat-exchange units are set up in thermal station to lower temperature of water in heat network to about 20°C. The return water is heated orderly by gas-water heat exchanger, absorption heat pump and the peak load heater. Compared with the traditional systems, this system runs with a greater circuit temperature drop so that the delivery capacity of the heat network increases dramatically. The heating capacity and the energy efficiency of the cogeneration plant is increased by the exhausted heat recovery from the flue gas. Finally, this paper has analyzed the advantages on energy-saving benefit, environmental benefit and economic benefit by one example that a gas cogeneration plant is reformed using the technology. [ABSTRACT FROM AUTHOR]

This paper aims to improve our knowledge of energy use and well-being in energy efficient office buildings. It explores the interrelations between forms and patterns of energy use on the one hand and user satisfaction, comfort, and well-being on the other hand. Findings are derived from qualitative and quantitative data collected in a recently finished research project in Austria. Fieldwork consisted of two qualitative case studies as well as an online-based survey amongst users of energy efficient office buildings. In addition, secondary data from energy-monitoring research was used to underpin the analysis. The results show that extremely low levels of energy use in office buildings can be aligned with high levels of well-being. Based on empirical findings the paper argues that both well-being and energy performance in office buildings are the result of a complex, on-going and intertwined process that involves various material and social elements. [ABSTRACT FROM AUTHOR]

The contribution of embodied energy (EE) and greenhouse gas emissions to building materials and structures has been recognized as significant, especially for nearly-zero energy-efficient buildings. The aim of this paper is to evaluate the composition of non-transparent structures of building envelopes from energy and environmental perspectives using the life-cycle assessment method. The study assesses environmental indicators such as EE from non-renewable resources and CO2eq and SO2eq emissions from proposed assemblies of building structures for nearly-zero energy wooden houses. Material compositions are also calculated in terms of selected thermal-physical aspects (U-value, phase shift of thermal oscillation, relaxation time) to ensure the reduction of energy consumption during building operation. All results are compared using a multi-dimensional evaluation approach through mathematical methods. The multi-criteria decision analysis demonstrates that material optimization of building structures is possible to ensure a marked reduction of the energy consumption and carbon footprint of buildings. [ABSTRACT FROM AUTHOR]

The buildings provide a significant contribution to total energy consumption and emissions. Integrated monitoring, analysis, and control methodologies can reduce this by up to 30%. However, the adoption of monitoring and control systems for building management and control applications is hampered by the unavailability of appropriate tool environments. In this paper a model-driven holistic system architecture integrating IT systems at design, construction, and operation stages of buildings is presented to provide optimized building operations. The main aim is to create a holistic environment for wireless embedded monitoring and control systems to increase the efficiency of the overall system development process and to exploit their potential for reduction of building energy consumption. To reach this objective, new methods, tools, and hardware covering integrated design, energy simulation models, and data warehouse technologies are introduced. The developed system, which is explained in this work, is applied in a residential building of the Turkish Prime Ministry Housing Development Administration in Istanbul, Turkey, and the results are elaborated to improve current building conditions. [ABSTRACT FROM AUTHOR]

This paper describes the results from a 12-month study of two prototype low energy dwellings built for Glasgow Housing Association (GHA). The houses are intended for mainstream and social tenure within Glasgow and contain a range of energy reducing features including one house with a thermally heavy clay block wall and one house using a conventional timber frame and both houses have sunspaces, Mechanical Ventilation with Heat Recovery (MVHR), solar thermal system and low energy lighting. The dwellings have been subject to an innovative monitoring strategy by MEARU, whereby test occupants (students recruited from the School of Architecture) have been asked to inhabit the buildings for six two-week periods using occupancy 'scripts' that determine their internal behaviour. The scenarios thus simulate varying patterns of occupancy in both houses simultaneously and the performance of the houses can then been compared. Indications are that although the clay block house had a poorer thermal performance, it did have other qualitative advantages, and consumption differences could be eliminated by exploiting the thermal mass. The performance of the active systems, including the MVHR system, was found to be problematic, and specific scenarios were undertaken to explore the implications of this. [ABSTRACT FROM AUTHOR]

This paper presents the new trends in the global "green" architecture, which is related to the performance of lowenergy buildings and their classification. Emphasized the great importance of this method of construction with respect to environmental protection and has been shown several examples of architectural performed worldwide. Their efficiency is confirmed in residential buildings, as well as large public and commercial buildings. The aim of this study was to analyze the experiences in their applications, their promotion and that wider application. [ABSTRACT FROM AUTHOR]

Energy consumption by the building sector constitutes a large portion of global energy use. Energy-efficient building technologies help to reduce heat gain in hot summer months, heat loss in cold winter months, and modify energy requirements in buildings. In the writers' paper, the effect of a proposed hollow roof (independent of and combined with a designed brick-cavity wall with brick projections and static sunshade) on indoor air temperature has been analyzed experimentally by constructing four rooms of habitable dimensions ( high) and studying average hourly temperatures for 1 year. Each room has a different combination of type of roof, wall, and static sunshade; hence, the difference in indoor air temperature of the rooms will primarily be attributable to differences in heat transferred through these building elements. The proposed hollow roof combined with the designed brick-cavity wall with brick projections and static sunshade lessened indoor air temperature in summer and increased indoor air temperature in winter mornings and nights. The writers' structures are thus useful for energy conservation per seasonal needs. [ABSTRACT FROM AUTHOR]

In this paper, experimental tests conducted on a new wood-based air-heating system for energy-efficient dwellings are presented. The main objective is to evaluate the resulting outlet temperatures and the amount of heat recovered by the ventilation air in order to assess feasibility and performance of coupling a mechanical ventilation heat-recovery unit and a triple concentric tube heat exchanger integrated into the chimney of a room-sealed wood-pellet stove to heat an entire house. After introducing the context of this work, the three main components of the combined system developed here, the coupling configuration adopted, as well as the protocol used and the sensors implemented on an experimental setup carried out in a laboratory are detailed in turn. Then, the heat transfer rates obtained from measurements for the various fluids as well as the effectiveness of the heat exchangers are presented and discussed. Finally, the resulting outlet temperatures of the three fluids exchanging in the triple concentric tube heat exchanger studied here are compared to those provided by analytical solutions obtained with a mathematical model. It is shown that heat transfer rates are predicted with a relative difference that is lower than 5% compared to experimental values and that such a system enables to cover all or most of heat losses in an energy efficient building. [ABSTRACT FROM AUTHOR]

This paper presents a new air-heating system concept for energy-efficient dwellings. It is a system designed to heat a low-energy building by coupling a heat-recovery ventilation system with a three-fluid heat exchanger located on the chimney of a wood-pellet stove. The proposed work focuses on the heat transfer that occurs between flue gases, the ventilation air and the combustion air within a triple concentric tube heat exchanger with no insulation at its outer surface. The main objective is to predict outlet temperature for the specific geometry of the heat exchanger studied here. Thus, the governing differential equations are derived for a counter-co-current flow arrangement of the three fluids. Then analytical solutions for the steady-state temperature distribution are obtained as well as the amount of heat transferred to the outside. An expression for the effectiveness of the heat exchanger is also proposed. Based on these results, calculations are performed on a case study to predict the fluid temperature distribution along the heat exchanger. Finally, a parametric study is carried out on this case study to assess the influence of the relevant parameters on the effectiveness of the heat exchanger. In addition, computation of heat losses to the outside justifies whether insulation is needed. [ABSTRACT FROM AUTHOR]

Abstract: With the increasing demand for more energy efficient buildings, the construction industry is faced with the challenge to ensure that the energy performance predicted during the design stage is achieved once a building is in use. There is, however, significant evidence to suggest that buildings are not performing as well as expected and initiatives such as PROBE and CarbonBuzz aim to illustrate the extent of this so called ‘performance gap’. This paper discusses the underlying causes of discrepancies between energy modelling predictions and in-use performance of occupied buildings (after the twelve month liability period). Many of the causal factors relate to the use of unrealistic input parameters regarding occupancy behaviour and facilities management in building energy models. In turn, this is associated with the lack of feedback to designers once a building has been constructed and occupied. The paper aims to demonstrate how knowledge acquired from Post-Occupancy Evaluation (POE) can be used to produce more accurate energy performance models. A case study focused specifically on lighting, small power and catering equipment in a high density office building is analysed and presented. Results show that by combining monitoring data with predictive energy modelling, it was possible to increase the accuracy of the model to within 3% of actual electricity consumption values. Future work will seek to use detailed POE data to develop a set of evidence based benchmarks for energy consumption in office buildings. It is envisioned that these benchmarks will inform designers on the impact of occupancy and management on the actual energy consumption of buildings. Moreover, it should enable the use of more realistic input parameters in energy models, bringing the predicted figures closer to reality. [Copyright &y& Elsevier]

Hydrological response of anthropogenic soil systems, including green roofs, has crucial importance in many fields of water engineering and management. As a consequence, there is an increasing need for modelling of the anthropogenic soil systems behaviour. To obtain empirical data, two green roof test beds were established on a green roof of University Centre for Energy Efficient Buildings, Czech Technical University in Prague. Each test bed is 1 m² in area and is instrumented for the runoff monitoring. One test bed was filled with less permeable local soil, the other with highly permeable commercial soil substrate, both were planted with stonecrops. Two simple deterministic lumped models - a nonlinear reservoir model and a linear reservoir cascade model - were used to assess the hydrological response of these green roof systems. The nonlinear reservoir model seems more appropriate for extensive green roof systems than the linear reservoir cascade model because of better description of rapid system reaction typical for thin soil systems. Linear reservoir cascade model frequently failed to mimic internal variability of observed hydrographs. In systems with high potential retention (represented by the test bed with local soil), episodically applied models that consider the same initial retention capacity for all episodes do not allow plausible evaluation of the actual episode-related retention. In such case, simulation model accounting for evapotranspiration between the rainfall events is needed. [ABSTRACT FROM AUTHOR]

The paper assesses thermomodernisation measures aimed at improving energy efficiency of dwelling houses in a city quarter in Upper Silesia, Poland. The area was encompassed by the city council's program of emission restriction that promoted energy saving activities. The assessment was carried out by means of thermographic examination. It confirmed the fact that the thermomodernisation measures taken so far provided considerable improvement, but did not solved all issues. Further works should be undertaken on the basis of thorough examination of the current condition of the buildings. [ABSTRACT FROM AUTHOR]

Abstract: Demand for energy efficient buildings has increased drastically in recent years and this trend will continue in the future. Insulating building elements will play a key role in meeting this demand by reducing heat losses through the building fabric. Due to their higher thermal resistance, Vacuum Insulation Panels (VIPs) would be a more energy efficient alternative to conventional building insulation materials. Thus, efforts to develop VIPs with characteristics suitable for applications to new and existing buildings are underway. This paper provides a review of important contemporary developments towards producing VIPs using various materials such as glass fibre, foams, perlite and fibre/powder composites. The limitations of the materials currently used to fabricate VIPs have not been emphasised in detail in previous review papers published. Selection criteria, methods to measure important properties of VIPs and analytical and numerical models presented in the past have been detailed. Limitations of currently employed design tools along with potential future materials such as Nano/microcellular foams and SiO x /SiN x coatings for use in VIPs are also described. [Copyright &y& Elsevier]

Abstract: The shortcomings or limitations of the traditional approach to developing energy efficient buildings are that they can not determine: (1) the ideal thermophysical properties of building envelope material, where “ideal” means that such material can use ambient air temperature variation and/or solar radiation efficiently to keep the indoor air temperature in the thermal comfort range with no additional space heating or cooling; (2) the best natural ventilation strategy; (3) the minimal additional energy consumption for space heating in winter or air-conditioning in summer. To overcome these problems, some new concepts for developing energy efficient buildings are put forward in this paper. They are the ideal thermophysical properties of the building envelope material, the ideal natural ventilation rate, and a minimal additional space heating or cooling energy consumption. A new approach for determining these properties is also developed. In contrast to the traditional approach (the thermophysical properties of building envelope material are known and constant so that the relating equations describing the indoor air temperature tend to be linear differential equations), the new approach solves the inverse problem (thermophysical properties, etc. of a buildings are unknown), whose solution can be a function instead of a value. As a first step, the ideal specific heat of the building envelope material for internal thermal mass is analyzed for buildings located in various cities in different climatic regions of China, such as Beijing, Shanghai, Harbin, Urumchi, Lhasa, Kunming and Guangzhou. We found that the ideal specific heat is composed of a basic value and an excessive one which is of δ function for the cases studied. Some limitations that would need further study are introduced in the end of the paper. [Copyright &y& Elsevier]

Abstract: This paper demonstrates that by understanding how energy is consumed in the manufacturing of reinforced concrete, designers can significantly reduce the overall embodied energy of structures. Embodied energy of products can vary from country to country. Therefore, to accurately estimate the embodied energy of reinforced concrete structures, data specific to the country where they are being constructed must be used. This paper presents the assessment of embodied energy in typical RC building structures in Ireland. The most common methods used to calculate EE are evaluated in this paper and the most suitable method was applied to reinforced concrete. The EE of a typical 30MPa concrete mix in Ireland is calculated to be 1.08MJ/kg. Notably cement is credited with 68% of the total EE. The major contributors of energy consumption are identified, which should aid to minimise energy consumption and optimise efficiency. A case study is presented which compares the EE of a typical reinforced concrete structure in Ireland using two concrete mix designs. The first uses Ordinary Portland Cement, while the second uses GGBS replacing half of the cement content. As expected, the EE of the GGBS mix is significantly lower (30%) than that of its counterpart. [Copyright &y& Elsevier]

Future Wireless Sensor Networks (WSNs) will be ubiquitous, large-scale networks interconnected with the existing IP infrastructure. Autonomic functionalities have to be designed in order to reduce the complexity of their operation and management, and support the dissemination of knowledge within a WSN. In this paper a novel protocol for energy efficient deployment, clustering and routing in WSNs is proposed that focuses on the incorporation of autonomic functionalities in the existing approaches. The design of the protocol facilitates the design of innovative applications and services that are based on overlay topologies created through cooperation among the sensor nodes. [ABSTRACT FROM AUTHOR]

Abstract: In today’s consumer electronics market, Java has become one of the most important programming languages for the rapid development of mobile applications – spanning from home appliances/controllers, mobile and communication devices, to network-centric applets. However, the demand for high-performance low-power Java-based consumer mobile applications puts forward new challenges to the system design and implementation. This paper analyzes the energy consumption, execution efficiency, and speed issues of Java applications in a typical consumer mobile device environment. By adopting a hardware-assisted approach, we introduce a Java accelerator with a companion Java virtual machine. The accelerator is designed in an asynchronous style, and can be integrated with most existing processors and operating systems. The core architecture, design philosophy, and implementation considerations are presented in detail in this paper. [Copyright &y& Elsevier]

Abstract: Thermally activated building systems (TABS) integrate the building structure as energy storage, and have proofed to be energy efficient and economic viable for the heating and cooling of buildings. Although TABS are increasingly used, in many cases control has remained an issue to be improved. In this paper, a method is outlined allowing for automated control of TABS in intermittent operation with pulse width modulation (PWM). This method represents one part of a TABS control solution with automatic switching between cooling and heating modes for variable comfort criteria which was published before. A first pulse width modulation control solution is derived based on a simple 1st order model of TABS. Then a second, even simpler solution is given that significantly reduces the tuning effort. Finally, the paper outlines a pulse width modulation control procedure and gives two application examples of the PWM control carried out in a laboratory test room. [Copyright &y& Elsevier]

In this paper, we present an Energy Efficient Secure Routing Protocol for Sensor Networks (ESecRout). The protocol uses the symmetric cryptography to secure messages, and uses a small cache in sensor nodes to record the partial routing path (previous and next nodes) to the destination. It guarantees that the destination will be able to identify and discard the tampered messages and ensure that the messages received are not tampered with. Simulation shows ESecRout's performance comparison with the non-secure routing protocol AODV [1] and the secure routing protocol SAODV [2]. Our protocol needs a little more route discovery overhead (about 8%) and costs a little more energy (about 8%) than AODV, but it performs much better than SAODV which needs much more route discovery overhead (about 33%) and costs much more energy (35%) than AODV. Simulation results also show that the packet delivery ratio and packet latency of AODV, SAODV, and ESecRout are almost the same. Thus, we show that our protocol ESecRout provides energy efficient secure routing. [ABSTRACT FROM AUTHOR]

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Abstract: The latest (4/04 and 5/04) versions of the Hong Kong Building Environmental Assessment Method (HK-BEAM), one covering new buildings and the other existing buildings, have been formally launched in 2005. The paper describes the building energy performance assessment method in these latest HK-BEAM versions. With the use of the energy budget approach, the assessment framework is applicable to a wide range of buildings that may comprise different mixes of premises types. The new scheme provides bonus credits for provisions that allow utilization of renewable energy sources. For existing buildings, it makes allowances for plant performance degradation and constraints to implementation of improvement measures in existing buildings. So far, the new assessment method has been applied to six building developments, including commercial complexes and residential developments. The assessment results are presented and discussed in the paper. [Copyright &y& Elsevier]

This paper presents work undertaken as part of the European H2020 project OptEEmAL (Optimized Energy Efficient Design Platform for Refurbishment at District Level), toward development of a decision-support platform for building and district refurbishment interventions. We describe a methodology for generation and evaluation of refurbishment scenarios for building and districts with particular emphasis on “active” energy conservation measures (i.e., installation or replacement of heating, ventilation, air conditioning (HVAC) systems) and related controls. The impact of HVAC and controls on energy and economic key performance indicators are usually neglected or very simplified in existing energy simulation tools. We apply a model-based approach to evaluate key-performance indicators related to energy consumption and energy costs in buildings and districts, such that possible refurbishment alternatives can be easily evaluated, thereby showing how a smart decision support tool will allow stakeholders to compare multiple alternatives quickly. By considering relevant case studies at building and district level, including refurbishment of heating and cooling plants, we highlight, in a simulation-based study, how the deployment of efficiency-based controls enable significant energy savings thanks to the exploitation of the model-based approach. This way, additional motivations for energy savings and ultimately for new investments in energy-related technologies are provided. [ABSTRACT FROM AUTHOR]

During the last decades, governments and companies have developed a wide range of strategies aimed at fostering the diffusion of Energy Efficiency Measures (EEMs)—i.e., the set of innovative materials and construction methods able to provide the same level of service by using less energy. In this regard, examining the ways in which households perceive EEMs, particularly their attributes and the related dimensions, could be particularly useful to promoting such technologies. By adopting a structural equation modeling approach, this study analyzes the perceived image of EEMs in Apulia (Italy), a region in which the adoption of eco-friendly practices, such as the installation of energy-efficient technologies, is inadequately diffused. Results reveal that the EEMs' latent dimensions (i.e., performance and sustainability ) have a significant impact on household adoption intention. Furthermore, among socio-demographic variables, household age moderates such an impact. The paper discusses some practical insights for persuasive communication and policy implications for sustainable development strategies. [ABSTRACT FROM AUTHOR]

One of the long-term challenges outlined within the UK Government's Energy White Paper (2011) is to cut both greenhouse gas (GHG) emissions and energy bills by improving household energy efficiency. As such, several energy-related initiatives have, in recent years, been promoted including the Community Energy Saving Programme. In this study, we explore how patterns of user consumption as influenced by occupant awareness and behaviour, can both positively and negatively influence policy initiative delivery. In so doing, we present the results from an extensive pre- and post-retrofit home energy use and performance survey of 150 properties located in Nottingham's Aspley ward, home of one of England's pilot CESP schemes. Our results show that whilst this specific initiative significantly improved home conditions and reduced energy consumption, it failed to achieve the predicted £300 annual savings on household energy bills. This was found to be largely attributed to occupants’ ingrained habits towards household energy use, higher comfort level preferences, (lack of) energy consumption awareness, and insufficient information provided to help residents better manage their home energy use following the retrofit. By exploring some of the core lessons learned from the survey, this research seeks to inform and improve the uptake and delivery of future retrofit initiatives. [ABSTRACT FROM AUTHOR]

A building influences its surrounding external environment, and its indoor environment is usually sensitive to its surroundings. In order to obtain a more accurate prediction of the indoor thermal behaviour of a building or a building stock, it is necessary to consider the interactions between the indoor and outdoor thermal environments. The modelling approach presented in this paper is based on a building energy model and the urban modelling tool SOLENE-Microclimat. A sensitivity analysis is undertaken to highlight the parameters which influence the performance of the building model. Then, the thermal indoor behaviour of a building is compared to in situ experimental measurements and the outdoor thermal environment is evaluated in terms of external surface temperatures. The model's accuracy and behaviour is evaluated and a crossover approach with the sensitivity analysis results is proposed. The model obtains a good level of performance for almost all variables, unless some external surface temperatures intervals. [ABSTRACT FROM AUTHOR]

Context-awareness has been considered as a crucial fact for developing context-driven control approaches in which sensing, and actuation tasks are performed according to the contextual changes. This could be done by including the occupants’ presence, number, actions and behaviours in up-to-date context taking into account the complex interlinked elements, situations, processes, and their dynamics. Many recent studies have shown that occupants’ information is a major leading source of uncertainty when developing occupancy-driven control approaches for energy efficient buildings. Comprehensive and real-time fine-grained occupancy information has to be, therefore, integrated in order to improve the performance of these control approaches. The work presented in this paper is towards the development of a holistic platform that combines recent IoT and Big data technologies for real-time occupancy detection. We focus mainly on occupants’ presence by comparing static and dynamic machine learning techniques. Experiments have been conducted and results are presented to assess the usefulness of the platform and the effectiveness of real-time machine learning strategies for data streams processing. [ABSTRACT FROM AUTHOR]

City authorities, community groups and retrofit installers need to identify suitable local areas and dwellings for installing energy retrofit measures. This paper presents a localised Geographical Information System (GIS) based approach that utilizes publicly-available national and local datasets on housing and energy to provide targeted low carbon measures across UK cities. The study uses a rapid city-level energy assessment approach to spatially identify suitable neighbourhoods for particular retrofit measures, based on relative energy use and fuel poverty ratings. A GIS-based carbon mapping model (called DECoRuM) is then used to estimate energy use and potential for energy reduction on a house-by-house level. The improvement measures are aggregated to encourage bulk installations and drive down installation costs. To identify an appropriate neighbourhood case study area, publicly available datasets were assessed for the town of Bicester (Oxfordshire, UK), which included Ordnance Survey Mastermap, Energy Performance Certificate data (EPC) and sub-national energy statistics available at lower layer super output area (LSOA). When the EPC data for Bicester were compared with the sub-national statistics for Bicester, the average difference was found to be ∼800 kWh. This is interesting as EPCs represent dwelling specific but modelled data whereas sub-national datasets represent actual but aggregated data. Superimposing the above datasets, a neighbourhood in southwest Bicester was selected as having the highest percentage of dwellings with energy consumption >300 kWh/m 2 /yr (EPC), most dwellings in need of wall insulation (EPC), second highest mean total energy consumption (sub-national), and third highest percentage of fuel poor dwellings (sub-national). House-level energy assessment in the selected area using DECoRuM showed that a package based approach comprising fabric and heating system upgrade and solar PVs emerged as the most effective. [ABSTRACT FROM AUTHOR]

Cloud computing data centers are growing rapidly in both number and capacity to meet the increasing demands for highly-responsive computing and massive storage. Such data centers consume enormous amounts of electrical energy resulting in high operating costs and carbon dioxide emissions. The reason for this extremely high energy consumption is not just the quantity of computing resources and the power inefficiency of hardware, but rather lies in the inefficient usage of these resources. VM consolidation involves live migration of VMs hence the capability of transferring a VM between physical servers with a close to zero down time. It is an effective way to improve the utilization of resources and increase energy efficiency in cloud data centers. VM consolidation consists of host overload/underload detection, VM selection and VM placement. Most of the current VM consolidation approaches apply either heuristic-based techniques, such as static utilization thresholds, decision-making based on statistical analysis of historical data; or simply periodic adaptation of the VM allocation. Most of those algorithms rely on CPU utilization only for host overload detection. In this paper we propose using hybrid factors to enhance VM consolidation. Specifically we developed a multiple regression algorithm that uses CPU utilization, memory utilization and bandwidth utilization for host overload detection. The proposed algorithm, Multiple Regression Host Overload Detection (MRHOD), significantly reduces energy consumption while ensuring a high level of adherence to Service Level Agreements (SLA) since it gives a real indication of host utilization based on three parameters (CPU, Memory, Bandwidth) utilizations instead of one parameter only (CPU utilization). Through simulations we show that our approach reduces power consumption by 6 times compared to single factor algorithms using random workload. Also using PlanetLab workload traces we show that MRHOD improves the ESV metric by about 24% better than other single factor regression algorithms (LR and LRR). Also we developed Hybrid Local Regression Host Overload Detection algorithm (HLRHOD) that is based on local regression using hybrid factors. It outperforms the single factor algorithms. [ABSTRACT FROM AUTHOR]

Decisions made in the early design stages critically determine a building’s life cycle environmental impacts and costs. Dynamic building performance feedback has the potential to improve design decision-making, but the best means of providing such feedback is not well understood. This paper evaluates the effectiveness of three visualization tools in helping designers make sustainable building design decisions. A charrette was conducted in which participants were tasked with minimizing carbon emissions and cost of an office building based on feedback from a scatterplot, histogram, and tornado diagram. Results demonstrate that designers achieved significant improvements in solution quality when feedback was present, with the scatterplot achieving a 20% improvement over conventional methods. The research quantifies the effectiveness of various visualization methods in helping designers create low-carbon, high-performing buildings and suggests that quantity and type of feedback should be carefully considered during the early stages of the sustainable design process. [ABSTRACT FROM AUTHOR]